| 摘要 |
PURPOSE:To detect the disconnection of a speaker even at the time of sound signal reproduction by detecting a current conducted to a speaker and comparing it with an input signal. CONSTITUTION:When a speaker 4 is disconnected, a current is not conducted to a current detecting resistance 3. Consequently, since a voltage is not generated at a rectifier 6, a signal only from a rectifier 7 is obtained at a comparator 8. In such a case it is judged at the comparator 8 that the speaker 4 is disconnected, a signal to be displayed at an indicator 9 is outputted and the indicator 9 displays that the speaker 4 is disconnected. When the speaker 4 is normally operated, the voltage from the rectifier 6 is set so as to be larger than the voltage from the rectifier 7 and an indicator 8 does not display the disconnection. |
